A special type of Pd-Al2O3 pellet, which included Pd in high weight percent as a hydrogen isotope separation material was prepared by a compression molding method. The pressure-composition isotherm and the plateau pressure of the Pd-Al2O3 hydrogen isotope system were determined by a volumetric method. The pellet has high hydrogen absorption ability even at 196 K, and the reaction rate is controlled by surface reaction. The hydrogen absorption capacity and the rate of the Pd-hydrogen system were unchanged by the addition of Al2O3 It was found that the Pd-Al2O3 pellet has high durability against repeated absorption-desorption cycles. There is no change in the absorption amount and the rate up to 1000 times of absorption-desorption cycles. (C) 2001 International Association for Hydrogen Energy. Published by Elsevier Science Ltd. All rights reserved.